Unit and integrated membrane operations for purification of spent single-phase detergent

Unit and integrated membrane operations were investigated for purification of a spent alkaline single-phase detergent from a CIP system in a milk production plant. The filtration experiments were performed in a concentration mode with the use of UF and NF modules differing in their configuration, MWCO, and polymer material. The performance of the modules was characterised in terms of their retention characteristics, hydraulic efficiency, and tendency to fouling. The results revealed that unit and integrated membrane processes were suitable for the recovery of spent cleaning baths containing single-phase detergents, and the permeates maintained their basic cleaning properties. Due to the greater selectivity of the NF module, integrated membrane operations resulted in a much greater modification of the composition of the single-phase detergent in comparison with unit UF processes.